究竟電阻同電壓成正比定係反比?????

V=IR (Ohm's Law)

V=Voltage
I=Current
R=Resistance

如果你話電流吾變(固定)既話,,

冇錯,,

電阻愈大,,

電壓既需求愈大,,

因為要得到同樣既電流,,

就上述例子,,

電阻同電壓成正比的

燈炮愈多，每個燈炮會愈光??

肯定吾會,,

串聯中負載愈多,,

負載電流愈少,,

並聯中負載愈多,,

每個負載會有一樣光度,,

但主電路電流會愈大!

大家講的 concept 不是 100% 對.

因為大家忘記了一個 fundemental 的 concept

就是 V = IR 只會 apply, 如果 R 是 ohmic conductor

R can be semiconductor or insulator

V, I, R 每個都會是 variable

就不會再 apply 了

究竟電阻同電壓成正比定係反比?????
Ohm's Law states that the current is proportional to the APPLIED voltage. Be aware that it is the "applied voltage" that is referred to, NOT the voltage across individual components if there are many components in a circuit.

咁姐係燈炮愈多，每個燈炮會愈光???????
For a given applied voltage to a number of light bulbs connected IN SERIES, the more the nunber of light bulbs, the less voltage each light bulb could share from the applied voltage. Thus giving to less brightness.

呢嗰問題歐姆定律已經表達清楚，
r = v / i
電阻同電壓成正比，同電流成反比。

2009-06-06 22:57:08 補充：
燈炟係電阻之一，但多個燈炟接法有分串聯同並聯，串聯時電阻增加，並聯時減少，所以根據公式，串聯時要增大電壓，但並聯時卻要增大電流。

V=IR

應該係正比。